#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<cstdio>
using namespace std;
typedef long long LL;
const int N = 5e5 + 10;
LL arr[N];
int n, m;
LL temp[N];
LL merge_sort(int l, int r)
{	
	if (l >= r) {
		return 0;
	}
	int mid = l + r >> 1;
	LL ans = merge_sort(l, mid) + merge_sort(mid + 1, r);
	int i = l;
	int j = mid + 1;
	int k = 0;
	while (i <= mid && j <= r) {
		if (arr[i] <= arr[j]) {
			temp[k++] = arr[i++];
		}
		else {
			temp[k++] = arr[j++];
			ans += mid - i + 1;
		}
	}
	while (i <= mid) {
		temp[k++] = arr[i++];
	}
	while (j <= r) {
		temp[k++] = arr[j++];
	}
	for (int i = l, j = 0; i <= r; i++, j++) {
		arr[i] = temp[j];
	}
	return ans;
}
int main()
{
	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		scanf("%d", &arr[i]);
	}
	cout << merge_sort(0, n - 1) << endl;
	return 0;
}